Alkylphosphonothioates



United States Patent 3,326,749 ALKYLPHGSPHONOTHIOATES John P. Chupp, Kirkwood, Mo., assignor to Monsanto Company, St. Louis, Mo., a corporation of Delaware No Drawing. Filed July 5, 1963, Ser. No. 293,193 Claims. (Cl. 167-30) This invention relates to new and useful alkylphosphonothioates. In addition this invention relates to insecticidal compositions containing at least one of these alkylphosphonothioates as an active ingredient.

The alkylphosphonothioates of this invention can be represented by the formula wherein n is a whole number from 1 to 3 and wherein R is an alkyl radical having 1 to 4 carbon atoms or an aromatic hydrocarbon radical of the benzene series having from 6 to 8 carbon atoms.

These alkylphosphonothiates can be prepared by reacting 3-trifiuoromethyl-4-cyanophenol with a halide or mixture of halides of the formula wherein R and n have the aforedescribed significance and wherein Z is a halogen of atomic number in the range of 16 to 36 (i.e. chlorine or bromine, preferably chlorine) in the presence of a hydrogen halide scavenging agent or mixtures thereof (e.g. sodium carbonate, potassium carbonate, triethylamine, triisopropylamine, dirnethylaniline, lutidine, l-pipecoline, pyridine, etc.) and the like in an amount sufiicient to absorb the hydrogen halide by-product. Where and when desired an inert organic liquid or solvent (e.g. benzene, toluene, xylene, acetone, butanone, dioxane, etc.) can be used. While a wide range of reaction conditions can be employed provided the system is fluid (Le. a temperature above the freezing point of the system up to and including the reflux temperature of the system) it is preferred to employ a reaction temperature in the range of from about C. to about 120 C. In general the halide reactant and 3-trifluoromethyl-4-cyanophenol will be employed in substantially equimolecular proportions. The scavenging agent can be added in an equivalent amount at the beginning of the reaction or throughout the course of the reaction.

As illustrative of the preparation of the alkylphosphonothioates of this invention but not limitatlve thereof is the following:

Example I To a suitable reaction vessel equipped with a thermometer, agitator and reflux condenser is charged approximately 80 parts by weight of benzene, approximately 4.1 parts by weight of 3-trifluoromethyl-4-cyanophenol, ap proximately 2.5 parts by weight of triethylamine, and approximately 4.3 parts by weight of O-phenyl methylphosphonothionyl chloride. While agitating the mixture is heated up to the reflux temperature and then refluxed for about five hours. The reaction mass is then cooled to room temperature and then quenched with water. The organic layer is separated and washed first with aqueous 3% sodium carbonate and then with water. The sowashed solution is then stripped of volatiles under vacuum. The oily residue upon recrystallizing gives solid O-phenyl O-(3-trifluoromethyl-4-cyanophenyl) methylphosphonothioate, M.P. 4447 C.

Analysis.-Theory: 8.69% P, 8.92% S, 3.90% N. Found: 8.51% P, 9.18% S, 3.63% N.

Example II Employing the procedure of Example I but replacing O-phenyl methylphosphonothionyl chloride with a substantially equimolecular amount of O-phenyl ethylphosphonothionyl bromide there is obtained O-phenyl O-(3- trifluoromethyl 4 cyanophenyl) ethylphosphonothioate which is insoluble in water.

Example III Employing the procedure of Example I but replacing O-phenyl methylphosphonothionyl chloride with a substantially equimolecular amount of O-o-tolyl ethylphosphonothionyl chloride there is obtained O-o-tolyl O-(3- trifluorornethyl 4 cyanophenyl) ethylphosphonothioate which is insoluble in water.

Example IV Employing the procedure of Example I but replacing O-phenyl methylphosphonothionyl chloride with a substantially equimolecular amount of O-m-tolyl methylphosphonothionyl chloride there is obtained O-m-tolyl O (4 cyano 3 trifluoromethylphenyl) methylphosphonothioate which is insoluble in water.

Example V Employing the procedure of Example I but replacing O-phenyl methylphosphonothionyl chloride with an equimolecular amount of O-3,5-xylyl n-propylphosphonothionyl chloride there is obtained O-3,5-xylyl O-(3-trifiuoromethyl-4-cyanophenyl) n-propylphosphonothioate which is insoluble in water.

Example VI Employing the procedure of Example I but replacing O-phenyl methylphosphonothionyl chloride with an equimolecular amount of O-m-tolyl methylphosphonothionyl chloride there is obtained O-m-tolyl O-(3-trifluoromethyl- 4-cyanophenyl) methylphosphonothioate which is insoluble in water.

Example VII Employing the procedure of Example I but replacing O-phenyl methylphosphonothionyl chloride with an equimolecular amount of O-n-propyl methylphosphonothionyl there is obtained O-n-propyl O-(3-trifluoromethyl-4- cyanophenyl) methylphosphonothioate which is insoluble in water.

Example VIII Employing the procedure of Example I but replacing O-phenyl methylphosphonothionyl chloride with an equimolecular amount of O-ethyl ethylphosphonothionyl chloride there is obtained O-ethyl O-(3-trifluoromethyl-4-cyanophenyl) ethylphosphonothioate which is insoluble in water.

Example IX Employing the procedure of Example I but replacing O-phenyl methylphosphonothionyl chloride with an equimolecular amount of O-n-butyl ethylphosphonothionyl bromide there is obtained O-n-butyl O-(3-trifiuoromethyl- 4-cyanophenyl) ethylphosphonothioate which is insoluble in water.

Example A Employing the procedure of Example I but replacing 3-trifluoromethyl-4-cyanophenol with an equimolecular amount of 4-cyanophenol there is obtained O-phenyl O- (4-cyanophenyl) methylphosphonothioate which is insoluble in water.

3 Example B Employing the procedure of Example I but replacing O-phenyl methylphosphonothionyl chloride with an equimolecular amount of O-(2-chloroethyl) methylphosphonothionyl chloride there is obtained O-(Z-chloroethyl) O-(4-cyanophenyl) methylphosphonothioate which is insoluble in water.

Example C Employing the procedure of Example I but replacing O-phenyl 'methylphosphonothionyl chloride with an equimolecular amount of O-n-propyl methylphosphonothionyl chloride there is obtained O-n-propyl O-(3-chloro-4- cyanophenyl) methylphosphonothioate which is insoluble in water.

The methods by which the alkylphosphonothioates of this invention are isolated will vary slightly with the reactants employed and the product produced. Further purification by selective solvent extraction or by absorptive agents such as activated carbon or clays can precede the removal of the inert organic liquid or solvent when such is employed. Additionally an inert organic solvent can be added to and in the purification by absorptive agents. However, the product is generally satisfactory for insecticidal purposes without further purification.

It will be understood that the terms insect and in secticide are used herein in their broad common usage to include spiders, mites, ticks, and like pests which are not in the strict biological sense classed as insects. Thus the usage herein conforms to the definitions provided by Congress in Public Law 104, the Federal Insecticide, Fungicide, and Rodenticide Act of 1947, section 2, subsection h, wherein the term insect is used to refer not only to those small invertebrate animals belonging mostly to the class Insecta, comprising six-legged, usually winged forms, as beetles, bugs, bees, flies, and so forth, but also to other allied classes of arthropods whose members are Wingless and usually have more than six legs, as spiders, mites, ticks, centipedes, and wood lice.

The phosphonothioates of this invention are effective against a wide variety of insect pests. As illustrative of the activity but not limitative thereof is the following:

A 1% by weight concentrate of the test chemical is prepared by dissolving the chemical in ml. of acetone. A 0.25 cc. tuberculin, B-D Yale syringe is filled with the concentrate and placed in a microinjection apparatus. The injector lever is pressed several times to make certain that no air bubbles are trapped in the needle and the needle is wiped with filter paper to remove any excess solution. The injector lever is pressed once to produce one microliter which is applied directly to the ventral side of the abdomen of each of 10 plum curculio, Conalrachelus nenuphar. After application each insect is released within observation dishes and held for 24 hours at room temperature and mortality observations made at the end of that time. This procedure is repeated at decreasing concentrations and the minimum weight concentration in micrograms per adult to give 50% mortality (i.e., the LD 50) determined. The following results were obtained:

Minimum conc. giving Test chemical: 50% mortality O-phenyl O- 3 -trifluoromethyl-4-cyanophenyl) methylphosphonothioate 0.06 O-n-propyl O-(3 trifluoromethyl-4-cyanophenyl) methylphosphonothioate 0.23 O-phenyl O-(4-cyanophenyl) methylphosphonothioate 0.32 O-(2-chloroethyl) O-(4-cyanophenyl) methylphosphonothioate 0.31 O-n-propyl O-(3-chloro-4-cyanophenyl) methylphosphonothioate 0.54

A 1% by weight concentrate is prepared by dissolving the test chemical in 10 ml. of acetone. A 0.25 cc. tuberculin, B-D Yale syringe is filled with this concentrate and placed in a microinjection apparatus. The injector lever is pressed several times to make certain no air bubbles are trapped in the needle and the needle is wiped with filter paper to remove excess solution. The injector lever is pressed once to produce one microliter which is applied directly to each of 12 lima bean leaf discs 0.25 inch in diameter. Single second instar southern armyworm larvae (Prodenia eridania) are placed on each disc and the disc encaged with a plastic cap. After 48 hours at room tem perature mortality observations are made. This procedure is repeated at decreasing concentrations and the minimum weight concentration in microgams per larva to give 50% mortality (i.e., the LD 50) determined. The results were as follows:

Minimum conc. giving Test chemical: 50% mortality O-phenyl O-(3-trifluoromethyl-4-cyanophenyl) methylphosphonothioate 5.1 O-n-propyl O-(3 trifluoromethyl-4-cyanophenyl) methylphosphonothioate O-phenyl O-(4-cyanophenyl) methylphosphonothioate 16.0 O-(2-chloroethyl) O-(4-cyanophenyl) methylphosphonothioate 23.0

Although the phosphonothioates of this invention are useful per se in controlling a wide variety of insect pests, it is preferable that they be supplied to the pests or to the environment of the pest or pests in a dispersed form in a suitable extending agent.

In the instant specification and appended claims it is to be understood that the term dispersed is used in its widest possible sense. When it is said that the phosphonothioates of this invention are dispersed, it means that particles of the phosphonothioates of this invention may be molecular in size and held in true solution in a suitable organic solvent. It mean-s further, that the particles may be colloidal in size and distributed throughout a liquid phase in the form of suspensions or emulsions or in the form of particles held in suspension by wetting agents. It also includes particles which are distributed in a semi-solid viscous carrier such as petrolatum or soap or other ointment base in which they may be actually dissolved in the semi-solid or held in suspension in the semi-solid with the aid of suitable wetting or emulsifying agents. The term dispersed also means that the particles may be mixed with and distributed throughout a solid carrier providing a mixture in particulate form, e.g. pellets, granules, powders, or dusts. The term dispersed also includes mixtures which are suitable for use as aerosols including solutions, suspensions, or emulsions of the phosphonothioates of this invention in a carrier such as dichloro-difiuoromethane and the like fluorochloroalkanes which boil below room temperature at atmospheric pressure.

In the instant specification and appended claims it is to be understood that the expression extending agent includes any and all of those substances in which the phosphonothioates of this invention are dispersed. It includes, therefore, the solvents of a true solution, the liquid phase of suspensions, emulsions or aerosols, the semi-solid carrier of ointments and the solid phase of particulate solids, e.g. pellets, granules, dusts and powders.

The exact concentration of the phosphonothioates of this invention employed in combatting or controlling insect pests can vary considerably provided the required dosage (i.e. toxic or lethal amount) thereof is supplied to the pests or to the environment of the pests. When the extending agent is a liquid or mixture of liquids (e.g. as in solutions, suspensions, emulsions, or aerosols) the concentration of the phosphonothioate employed to supply the desired dosage generally will be in the range of 0.001 to 50 percent by weight. When the extending agent is a semi-solid or solid, the concentration of the phosphonothioate employed to supply the desired dosage generally Will be in the range of 0.1 to 25 percent by weight. From a practical point of view, the manufacturer must supply the agriculturist with a low-cost concentrate or spray base or particulate solid base in such form that, by merely mixing with water or solid extended (e.g., powdered clay or talc) or other low-cost material available to the agriculturist at the point of use, he will have an easily prepared insecticidal spray or particulate solid. In such a concentrate composition, the phosphonothioate generally will be present in a concentration of 5 to 95 percent by Weight, the residue being any one or more of the well known insecticidal adjuvants, such as the various surface active agents (e.g. detergents, a soap or other emulsifying or wetting agent), surface-active clays, solvents, diluents, carrier media, adhesives, spreading agents, humectants, and the like.

There are a large number of organic liquids which can be used for the preparation of solutions, suspensions or emulsions of the phosphonothioates of this invention. For example, isopropyl ether, acetone, methyl ethyl ketone, dioxane, cyclohexanone, carbon tetrachloride, ethylene dichloride, tetrachloroethane, hexane, heptane and like higher liquid alkanes, hydrogenated naphthalenes, solvent naphtha, benzene, toluene, xylene, petroleum fractions (e.g. those boiling almost entirely under 400 F. at atmos-pheric pressure and having a flash point above about 80 F., particularly kerosene), mineral oils having an unsulfonatable residue above about 80 percent and preferably above about 90 percent. In those instances wherein there may be concern about the phytotoxicity of the organic liquid extending agent a portion of same can be replaced by such low molecular weight aliphatic hydrocarbons as dipentene, dissobutylene, propylene trimer, and the like or suitable polar organic liquids such as the aliphatic ethers and the aliphatic ketones containing not more than about carbon atoms as exemplified by acetone, methyl ethyl ketone, dissobutyl ketone, dioxane, isopropyl ether, and the like. In certain instances, it is advantageous to employ a mixture of organic liquids as the extending agent.

When the phosphonothioates of this invention are to be supplied to the insect pests or to the environment of the pests as aerosols, it is convenient to dissolve them in a suitable solvent and disperse the resulting solution in dichlorodifiuoromethane or like chlorofiuoroalkane which phosphonothioate of this invention either per se or in the form of an organic solution thereof in water with the aid of a water-soluble surfactant. The term surfactant as employed here and in the appended claims is used as in volume II of Schwartz, Perry and Berchs Surface Active Agents and Detergents (1958, Interscience Publishers, Inc., New York), in place of the expression emulsifying agent to connote generically the various emulsifying agents," dispersing agents, wetting agents and spreading agents that are adapted to be admixed with the active compounds of this invention in order to secure better wetting and spreading of the active ingredients in the water vehicle or carrier in which they are insoluble through lowering the surface tension of the water (see also Frear, Chemistry of Insectcides, Fungicides and Herbicides, second edition, page 280). These surfactants include the well-known capi1lary-active substances which may be anion-active (or anionic), cation active (or cationic), or non-ionizing (or non-ionic) which are described in detail in volumes I and II of Schwartz, Perry and Berchs Surface Active Agents and Detergents (1958, Interscience Publishers, Inc., New York), and also in the November 1947 issue of Chemical Industries (pages 811- 824), in an article entitled, Synthetic Detergents, by

John W. McCutcheon and also in the July, August, September and October 1952 issues of Soap and Sanitary Chemicals under the title, Synthetic Detergents. The disclosures of these articles with respect to surfactants, i.e. the anion-active cation-active and non-ionizing capillary active substances, are incorporated in this specification by reference in order to avoid unnecessary enlargement of this specification. The preferred surfactants are the watersoluble anionic surface-active agents and the water-soluble non-ionic surface active agents set forth in U.S. 2,846,398 (issued Aug. 5, 1958). In general it is prefered that a mixture of water-soluble anionic and water-soluble nonionic surfactants be employed.

The phosphonothioates of this invention can be dispersed by suitable methods (e.g. tumbling or grinding) in solid extending agents either of organic or inorganic nature and supplied to the insect pests environment in particulate form. Such solid materials include for example, tricalcium phosphate, calcium carbonate, kaolin, bole, kieselguhr, talc, fullers earth, bentonite, pyrophillite, diatomaceous earth, calcined magnesia, volcanic ash, sulfur and the like inorganic solid materials, and include for example, such materials of organic nature as powdered cork, powdered wood, and powdered walnut shells. The preferred solid carriers are the adsorbent clays, e.g. bentonite. These mixtures can be used for insecticidal purposes in the dry form, or, by addition of water-soluble surfactants or wetting agents the dry particulate solids can be rendered wettable by water so as to obtain stable aqueous dispersions or suspensions suitable for use as sprays.

For special purposes the phosphonothioates of this invention can be dispersed in a semi-solid extending agent such as petrolatum or soap (e.g. sodium stearate or oleate or palmitate or mixtures thereof) with or without the aid of solubility promotors and/or surfactants or dispersing agents.

In all of the forms described above the dispersions can be provided ready for use in combatting insect pests or they can be provided in a concentrated form suitable for mixing With or dispersing in other extending agents. As illustrative of a particularly useful concentrate is an intimate mixture of phosphonothioate of this invention with a water-soluble surfactant which lowers the surface tension of water in the Weight proportions of 0.1 to 15 parts of surfactant with suflicient of the phosphonothioate of this invention to make 100 parts by weight. Such a concentrate is particularly adapted to be made into a spray for combatting various forms of insect pests by the addition of water thereto. As illustrative of such a concentrate is an intimate mixture of parts by weight of O-phenyl O- (3trifluoromethyl-4-cyanophenyl) methylphosphonothioate and 5 parts by weight of a water-soluble non-ionic surfactant such as the polyoxyethylene derivative of sorbitan monolaurate.

Another useful concentrate adapted to be made into a spray for combatting a variety of insect pests is a solution (preferably as concentrated as possible) of a phosphonothioate of this invention in an organic solvent therefor. The said liquid concentrate preferably contains dissolved therein a minor amount (e.g. 0.5 to 10 percent by weight of the weight of the new insecticidal agent) of a surfactant (or emulsifying agent), which surfactant is also water-soluble. As illustrative of such a concentrate is a solution of O-n-propyl O-(3-trifluoromethyl-4-cyanophenyl) methylphosphonothioate in benzene which solution contains dissolved therein a water-soluble polyoxyethylene glycol non-ionic surfactant'and a Water-soluble alkylaryl sulfonate anionic surfactant.

Of the surfactants aforementioned in preparing the various emulsifiable, wettable or dispersible compositions or concentrates of this invention, the anionic and non-ionic surfactants are preferred. Of the anionic surfactants, the particularly preferred are the well known water-soluble alkali metal alkylaryl sulfonates as exemplified by sodium decylbenzene sulfonate and sodium dodecylbenzene sulfonate. Of the non-ionic surfactants, the particularly preferred are the water-soluble polyoxyethylene derivatives of alkylphenols (particularly isooctylphenol) and the water-soluble polyoxyethylene derivatives of the monohigher fatty acid esters of hexitol anhydrides (e.g. sorbitan). These materials in general contain to 30 moles of ethylene oxide per mole of the hexitol anhydride or the alkylphenol.

In all of the various dispersions described hereinbefore for insecticidal purposes, the active ingredient can be one or more of the compounds of this invention. The compounds of this invention can also be advantageously employed in combination with other pesticides, including, for example, nematocides, bactericides, and herbicides. In this manner it is impossibleto obtain mixtures which are effective against a wide variety of pests and other forms of noxious life.

In controlling or combatting insect pests the phosphonothioates of this invention either per se or compositions comprising same are supplied to the insect pests or to their environment in a lethal or toxic amount. This can be done by dispersing the new insecticidal agent or inseoticidal composition comprising same in, on or over an infested environment or in, on or over an environment the insect pests frequent, e.g., agricultural soil or other growth media or other media infested with insect pests or attractable to the pests for habitational or sustenance or propagational purposes, in any conventional fashion which permits contact between the insect pests and the phosphonothioates of this invention. Such dispersing can be brought about by applying sprays or particulate solid compositions to a surface infested with the insect pests or attractable to the pests, as for example, the surface of an agricultural soil or other media such as the above ground surface of plants by any of the conventional methods, e.g. power clusters, boom and hand sprayers, and spray dusters. Also for sub-surface application such dispersing can be carried out by simply mixing the new insecticidal agent per se or insecticidal spray or particulate solid compositions comprising same with the infested environment or with the environment the insect pests frequent, or by employing a liquid carrier for the new insecticidal agent to accomplish sub-surface penetration and impregnation therein.

While this invention has been described with respect to certain embodiments, it is to be understood that it is not so limited and that variations and modifications thereof obvious to those skilled in the art can be made without departing from the spirit and scope thereof.

What is claimed is:

1. An insecticidal composition comprising an alkylphosphonothioate of the formula wherein n is a whole number from 1 to 3 and wherein R is selected from the group consisting of alkyl radicals having from 1 to 4 carbon atoms and aromatic hydrocarbon radicals of the benzene series having from 6 to 8 carbon atoms, dispersed in an extending agent.

2. An insecticidal composition comprising an alkylphosphonothioate of the formula wherein n is a whole number from 1 to 3 and wherein R is selected from the group consisting of alkyl radicals having from 1 to 4 carbon atoms and aromatic hydrocarbon radicals of the benzene series having from 6 to 8 carbon atoms, dispersed in an extending agent selected from the group consisting of solid and semi-solid extending agent, the composition containing 0.1 to 25 percent by weight of said alkylphosphonothioate.

3. An insecticidal composition comprising an alkylphosphonothioate of the formula I! R-OP0 (CH2) nH wherein I1. is a whole number from 1 to 3 and wherein R is selected from the group consisting of alkyl radicals having from 1 to 4 carbon atoms and aromatic hydrocarbon radicals of the benzene series having from 6 to 8 carbon atoms, dispersed in a liquid extending agent, the composition containing 0.001 to 50 percent by weight of said alkylphosphonothioate.

4. An insecticidal concentrate comprising a methylphosphonothioate of the formula wherein R is an aromatic hydrocarbon radical of the benzene series having from 6 to 8 carbon atoms, and an insecticidal adjuvant, said concentrate containing from 5 to percent by weight of the methylphosphonothioate.

5. An insecticidal concentrate comprising a methylphosphonothioate of the formula wherein R is an aromatic hydrocarbon radical of the henzene series having from 6 to 8 carbon atoms, dispersed in an organic solvent therefor and having dissolved therein a minor amount of a surfactant, said concentrate forming an emulsion with water upon agitation therewith.

6. An insecticidal concentrate adapted to be made into a sprayable composition by the addition of water comprising a methylphosphonothioate of the formula wherein R is an aromatic hydrocarbon radical of the benzene series having from 6 to 8 carbon atoms in admixture with a water-soluble surfactant in the weight proportion of 0.1 to 15 parts of surfactant and sufficient of said methylphosphonothioate to make parts by weight.

7. The method of controlling insects which comprises contacting the insects with a toxic amount of at least one alkylphosphonothioate of the formula wherein n is a whole number from 1 to 3 and wherein R is selected from the group consisting of alkyl radicals having from 1 to 4 carbon atoms and aromatic hydrocarbon radicals of the benzene series having from 6 to 8 carbon atoms.

8. The method of controlling insects which comprises contacting the insects with a toxic amount of at least one methylphosphonothioate of the formula wherein R is an aromatic hydrocarbon radical of the benzene series having from 6 to 8 carbon atoms.

9 9. The method for protection of plants against insect attack which comprises applying to the plant an insecticidal amount of at least one alkylphosphonthioate of the formula (llFa HmH wherein n is a whole number from 1 to 3 and wherein R is selected from the group consisting of alkyl radicals hav ing from 1 to 4 carbon atoms and aromatic hydrocarbon radicals of the benzene series having from 6 to 8 carbon atoms.

10. The method for protection of plants against insect attack which comprises applying to the plant an insecticidal amount of at least one methylphosphonothioate 0f the formula wherein R is an aromatic hydrocarbon radical of the benzene series having from 6 to 8 carbon atoms.

References Cited UNITED STATES PATENTS 2,956,921 10/ 1960 Santmyer et a1. 167-30 2,995,487 8/1961 Jones et a1. 167-30 3,078,212 2/1963 NeWallis et a1. 260-461 3,082,147 3/1963 Newallis et a1. 167-30 3,100,790 8/1963 Oertel et a1. 260-461 3,102,901 9/1963 Fields 260-461 3,105,819 10/1963 Anderson 252-499 3,112,271 11/1963 Calhoun 252-466 3,131,120 4/1964 Chllpp et a1. 167-30 3,250,826 5/1966 Tamura et al. 260-940 3,281,503 10/1966 Oswald 260-935 3,162,672 12/1964 Richert et a1 260-461 ALBERT T. MEYERS, Primary Examiner.

JULIUS S. LEVITT, Examiner.

GEORGE A. MENTIS, Assistant Examiner. 

1. AN INSECTICIDAL COMPOSITION COMPRISING AN ALKYLPHOSDPHONOTHIOATE OF THE FORMULA 